Early Clinical Infancy Outcomes for Microcephaly and/or SGA Zika-exposed Infants

BACKGROUND: Antenatal Zika virus (ZIKV) exposure may lead to adverse infant outcomes including microcephaly and small for gestational age (SGA). ZIKV-exposed infants with either a diagnosis of microcephaly [proportional (PM) or disproportional (DM)] or SGA at birth were evaluated with anthropometric measurements and health outcomes. METHODS: Infants included had laboratory-confirmed ZIKV-exposure in Brazil. Classification of PM, DM, or SGA was based on head circumference and weight measurements. Growth parameters and clinical outcomes were recorded in the first year of life with analyses performed. RESULTS: Among the 156 ZIKV-exposed infants, 14 (9.0%) were SGA, 13 (8.3%) PM, 13 (8.3%) DM, and 116 (74.4%) infants with neither SGA nor microcephaly (NSNM). High rates of any neurologic, ophthalmologic, and hearing abnormalities were observed for PM (100%), DM (100%), and SGA (42.9%) versus NSNM infants (18.3%) (p<0.001); OR 3.4(95% CI 1.1-10.7) for SGA versus NSNM. Neuroimaging abnormalities were seen in 100% of PM and DM and 42.9% of SGA versus NSNM infants (16%) (p<0.001); OR 3.9(95% CI 1.2-12.8) for SGA versus NSNM. Growth rates by Z-score, particularly for microcephaly infants, were initially poor after birth but showed improvement beyond four months of life. CONCLUSION: ZIKV-exposed infants with microcephaly (PM and DM) had similarly high rates of adverse outcomes. While SGA infants had lower rates of adverse outcomes compared to those with microcephaly, notable adverse outcomes were observed in some; their odds of having adverse outcomes were three to four-times greater compared to NSNM infants. For microcephalic infants, growth measurements by Z-score may show improvement beyond four months of life.